Apparatus for use in a paving operation

ABSTRACT

A primary furnace device is adapted to heat a paved area to a first predetermined temperature. A secondary furnace device is adapted to heat the paved area to a second predetermined temperature via a multi-stage process having at least two heating zones interspersed with at least one soaking zone. A heater/shaver is adapted to heat the paved area to a third predetermined temperature and to shave the heated paved area to a predetermined depth to create a first mixture located upon a substrate. A mixer/finisher is adapted to collect the first mixture, mix the first mixture, and produce recycled pavement. The primary furnace device, secondary furnace device, heater/shaver, and mixer/finisher travel in series along the paved area in a longitudinal direction. A method of recycling pavement is also provided.

TECHNICAL FIELD

The present invention relates to an apparatus for use in a pavingoperation.

BACKGROUND OF THE INVENTION

When a roadway, parking lot, or other paved area becomes sufficientlyworn from use, weather, or other causes, it is often desirable toresurface or repave the paved area. In conventional resurfacingprocesses, pavement is mechanically removed from the paved area, by ascarifier or a rotary milling machine. The pavement may be preheated tofacilitate such removal. The loose pavement produced by such a processmay be recycled. The loose pavement is treated to renew the materialproperties of the asphalt already present within the loose pavement. Therecycled loose pavement may be laid back down on the substrate ortransported away for use in another paved area.

SUMMARY OF THE INVENTION

According to an embodiment of the present invention, an apparatus isdescribed. A primary furnace device is adapted to heat a paved area to afirst predetermined temperature. A secondary furnace device is adaptedto heat the paved area to a second predetermined temperature via amulti-stage process having at least two heating zones interspersed withat least one soaking zone. A heater/shaver is adapted to heat the pavedarea to a third predetermined temperature and to shave the heated pavedarea to a predetermined depth to create a first mixture located upon asubstrate. A mixer/finisher is adapted to collect the first mixture, mixthe first mixture, and produce recycled pavement. The primary furnacedevice, secondary furnace device, heater/shaver, and mixer/finishertravel in series along the paved area in a longitudinal direction.

According to an embodiment of the present invention, a furnace devicefor heating pavement during a paving operation is described. A heatingsystem has a plurality of heating zones. The plurality of heating zonesare arranged in a longitudinal direction relative to the direction ofmovement of the furnace device relative to the pavement. Each of theheating zones is separately controllable and spaced apart from eachother by at least one soaking zone. A suspension system supports theplurality of heating zones for movement along the paved area.

According to an embodiment of the present invention, a pavementmixer/finisher for processing pavement during a paving operation isdescribed. A suspension system is adapted to support the mixer/finisherfor movement along a paved area. A mixing plant includes a drum and anauger. The auger is rotatable relative to the drum. The drum extendssubstantially parallel to the paved area. The mixing plant is adapted totransform the first mixture into recycled pavement. An intake device isadapted to deliver the first mixture to the mixing plant. An outputdevice is adapted to deliver the recycled pavement from the mixingplant.

According to an embodiment of the present invention, a method ofrecycling pavement is described. A paved area is heated to a firstpredetermined temperature. The paved area is heated to a secondpredetermined temperature via a multi-stage process with a furnacedevice having first and second heating zones fixedly connected to eachother and spaced apart from each other. The paved area is heated to athird predetermined temperature. The heated paved area is shaved to apredetermined depth to create a first mixture located upon a substrate.The first mixture is collected. The first mixture is mixed. Recycledpavement is produced. The steps of heating the paved area to the firstpredetermined temperature, heating the paved area to the secondpredetermined temperature, heating the paved area to the thirdpredetermined temperature, shaving the heated paved area, collecting thefirst mixture, mixing the first mixture, and producing recycled pavementoccur in series.

According to an embodiment of the present invention, a system forrecycling pavement is described. Means for heating a paved area to afirst predetermined temperature is provided. Means for heating the pavedarea to a second predetermined temperature via a multi-stage processwith at least two heating periods interspersed with at least one soakingperiod is provided. The means for heating the paved area to a secondpredetermined temperature includes a furnace device having first andsecond heating zones fixedly connected to each other and spaced apartfrom each other. Means for heating the paved area to a thirdpredetermined temperature is provided. Means for shaving the heatedpaved area to a predetermined depth to create a first mixture locatedupon a substrate is provided. Means for collecting the first mixture isprovided. Means for mixing the first mixture is provided. Means forproducing recycled pavement is provided. The means for heating the pavedarea to the first predetermined temperature, means for heating the pavedarea to the second predetermined temperature, means for heating thepaved area to the third predetermined temperature, means for shaving theheated paved area, means for collecting the first mixture, means formixing the first mixture, and means for producing recycled pavementoperate in series along the paved area in a longitudinal direction.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention, reference may be made tothe accompanying drawings, in which:

FIG. 1 is a schematic side view of an exemplary embodiment of amulti-stage apparatus according to the present invention;

FIG. 2 is a schematic cross-sectional side view of a first furnacedevice of the multi-stage apparatus depicted in FIG. 1;

FIG. 3 a is a schematic partial side view of the furnace device depictedin FIG. 2;

FIG. 3 b is a schematic partial plan view of the furnace device depictedin FIG. 2;

FIG. 4 is a schematic partial plan view of the furnace device depictedin FIG. 2;

FIG. 5 is a schematic process view of the furnace device depicted inFIG. 2;

FIG. 6 is a schematic cross-sectional side view of a second furnacedevice of the multi-stage apparatus depicted in FIG. 1; and

FIG. 7 is a schematic cross-sectional side view of a heater/shaver ofthe multi-stage apparatus depicted in FIG. 1; and

FIG. 8 is a schematic partial cross-sectional side view of amixer/finisher of the multi-stage apparatus depicted in FIG. 1.

DESCRIPTION OF EMBODIMENTS

In accordance with the present invention, FIG. 1 depicts an exemplaryembodiment of a multi-stage apparatus 100 for use in paving a road,parking lot, or other paved area (shown generally at 102, actuallyextending out of and into the plane of FIG. 1). The multi-stageapparatus 100 may be used for repaving or in-place recycling of pavementin a paving application, such as a road or parking lot resurfacing.

The multi-stage apparatus 100 includes at least one primary pavementheater or furnace device 104 and at least one secondary pavement heateror furnace device 106. The primary and secondary furnace devices 104 and106 are adapted to heat the pavement 108 of a paved area 102 to apredetermined depth and temperature. The predetermined depth andtemperature are chosen to soften the pavement 108 in a desired mannerfor removal from a substrate 110 (a portion of which is shown in cutawayin FIG. 1). The substrate 110 may be other pavement or any othersuitable material. The predetermined depth and temperature may be basedon an atmospheric temperature, a composition of the pavement 108, athickness of the pavement 108, a thickness of the substrate 110, amaterial of the substrate 110, other functions performed by the primaryand secondary furnace devices 104 and 106, or any other desired factorsor combinations thereof.

The primary furnace device 104 includes a furnace body 212, shown ingreater detail in FIG. 2, which is adapted to heat the paved area 102 toa first predetermined temperature. The furnace body 212 includes a fuelsource 214, a furnace body frame 216, and a plurality of heatingelements or heads 218 (most left unlabeled for clarity). The fuel source214 may be a gas tank, such as the propane tank 214 shown in FIG. 2, ormay be a fuel cell, battery, or any other suitable fuel source 214. Thefurnace body frame 216 is adapted to support and optionally enclose thefuel source 214. The furnace body frame 216 includes a plurality offurnace body supports 220 which are connected to make up the furnacebody frame 216. The furnace body supports 220 may be connected bywelding, riveting, bolting, or the like. The furnace body supports 220may provide a framework for substantially enclosing the fuel source 214with a suitable furnace covering system (labeled 122 in FIG. 1, omittedfrom FIG. 2 for clarity), such as an enclosure of sheet metal,fiberglass, or the like.

A suspension system 224 is adapted to support the furnace body 212 formovement in a longitudinal direction along the paved area 104. Thesuspension system 224 includes a plurality of wheels 226, a suspensionframe 228 supported by the wheels 226, and a heating frame (showngenerally at 230) carried by the suspension frame 228. The heating frame230 is adapted to movably hold the heating heads 218 a predetermineddistance from the pavement 108. The distance between the heating heads218 and the pavement 108 of the primary furnace device 204 may beoptimized to heat the pavement 108 to the first predetermined depth andtemperature.

In the primary furnace device 104 shown in FIG. 2, the heating frame 230is comprised of first and second heating frames 230 a and 230 b, whichcan be controlled, powered, moved, and otherwise utilized separately, ifdesired. Alternately, the first and second heating frames 230 a and 230b of the primary furnace device 104 may be considered to make up acombined heating frame 230. The first and second heating frame 230 a and230 b components of this heating frame 230 may be moved and mounted in aunitary manner but may also be controlled separately to achieve adifferential heat application to the pavement 108, when desired. Eachheating frame 230 will be generally presumed herein to be of a basicone-piece type for simplicity of discussion, though one of ordinaryskill in the art can readily provide independently movable and/oroperable first and second heating frames 230 a and 230 b for aparticular application of the present invention.

The distance between the heating heads 218 and the pavement 108 may bechanged as desired during operation of the primary furnace device 204 bymoving the heating frame 230 with a height adjustment mechanism 232. Theheight adjustment mechanism 232 of the heating frame 230 may be of anysuitable type, such as a piston cylinder arrangement, a rack-and-pinionsystem, a cotter pin and suspension arm arrangement, or the like.

An exemplary arrangement of the plurality of heating heads 218 of theprimary furnace device 104 is shown in the grid-type layout of FIGS. 3 aand 3 b. The plurality of heating heads 218 may define a plurality ofseparately controllable heating zones 334 a, 334 b, and 334 c, which arearranged in the longitudinal direction relative to the direction ofmovement of the primary furnace device 104 relative to the pavement 108.The suspension system 224 supports the plurality of heating zones 334for movement along the paved area 102.

An operator of the primary furnace device 104 may control the heatoutput by each heating zone 334 based upon the temperature of thepavement 108 beneath that heating zone 334, and thereby use theplurality of adjacent heating zones 334 to heat the pavement 108 to thefirst predetermined temperature. Although three heating zones 334 a, 334b, and 334 c are shown, any desired number of heating zones may beprovided, and in any desired configuration (e.g., split across multiplehearing frames 230 a, 230 b, and the like).

An experienced operator may be able to determine whether the pavement108 has reached the predetermined temperature based upon the appearanceof the pavement 108, a sensed temperature at a certain distance from thepavement 108, or another observable factor combined with the operator'sexperience and training. The operator may then control each heating zone334 of the primary furnace device 104 individually to bring the pavement108 to the first predetermined temperature without overheating andscorching the topmost surface of the pavement 108.

The longitudinal arrangement of heating zones 334 a, 334 b, 334 c allowsfor ongoing temperature observation and adjustment as the pavement 108is heated. Therefore, the operator has greater control of thetemperature of the entire pavement 108 with the use of heating zones 334than if the pavement 108 were merely subjected to one pass of afixed-temperature array of heating heads 218.

The primary furnace device 104 includes a heating system 236 adapted toprovide air to the heating heads 218. The heating system 236 includes atleast one fan 238 and an air box 240. The fan 238 is located within thefurnace body 212, which may be enclosed by the furnace covering system122. The air box 240 is associated with the heating frame 230 and isadapted to absorb heat, directly or indirectly, from the heating frame230. The heating frame 230 may form a portion of the structure of theair box 240, but will be discussed as a separate structure herein forclarity. Because FIG. 2 depicts an example configuration of the primaryfurnace device 104 which includes first and second heating frames 230 aand 230 b, this Figure also shows a plurality of heating systems 236,236′, with each heating system having a fan 238, 238′ and an air box240, 240′ and being associated with a heating frame 230 a, 230 b. Eachof the heating systems 236, 236′ will operate similarly and both willthus be discussed as a single heating system 236 (with relatedcomponents) below. It is contemplated, however, that in an embodiment ofthe primary furnace device 104 including a single heating frame 230,only a single heating system 236 may be provided.

The fan 238 draws ambient air from inside the furnace body 212 and sendsthe ambient air to the air box 240. The air circulated through the airbox 240 absorbs heat, which has traveled into the air box 240 from theheating frame 230, the heating heads 218, and the pavement 108.Accordingly, the air circulated through the air box 240 cools theheating frame 230 to help prevent damage to the heating frame 230.

The heating system 236 provides the ambient air from within the furnacebody 212 to the heating heads 218 through use of the air box 240. Asdepicted in plan view in FIG. 4, the air box 240 is a ductwork structureadjacent the heating frame 228 and connected to the fan 238 by atransmission duct 242 (shown in FIG. 2). One possible airflow routing isshown by the arrows in FIG. 4. Air is passed to the air box 240 from thetransmission duct 242 via the air box's air intake 444. Once in the airbox 240, the airflow circulates to the heating heads 218, optionallyunder pressure from the fan 238. The airflow may roam freely within arelatively open air box 240 structure or may be directed to one or moreheating heads 218 through at least one circulation duct 446 (severalleft unlabeled for clarity), such as the sample grid arrangement of aplurality of circulation ducts shown in FIG. 4.

Regardless of the way in which the airflow is routed, the air box 240 isin fluid communication with an air intake (not shown) of each heatinghead 218 to supply heated air, which may be under pressure, for thecombustion process. The fuel source 214 supplies fuel for combustionthrough a fuel line (not shown in this view), which runs between thefuel source 214 and at least one heating head 218.

Any suitable heating head 218 may be used in the multi-stage apparatus100 of the present invention. For example, a heating head 218 which maybe suitable for certain applications of the present invention isdisclosed in co-pending U.S. patent application Ser. No. ______, “Burnerfor Paving Apparatus”, attorney docket no. ARS-018374 PRI, filedconcurrently with the instant application and incorporated wholly byreference herein.

In the exemplary embodiment of the Figures, the fuel supplied is propaneand the heating head 218 includes an ignition source (not shown) tospark the combustion process. The heat resulting from the combustion ofthe fuel and the heated air is supplied to the pavement 108 by theheating head 218. By supplying heated air to the heating heads 218through the air box 240, the primary and secondary furnace devices 104and 106 require less fuel to achieve a desired heat output from thecombustion process than if ambient air were used for combustion.

As shown in FIG. 5, a fuel valve 548 is associated with each heatingzone 344. Each fuel valve 548 may be individually controlled to adjustan amount of heat supplied by the heating heads 218 of that heating zone334 to the pavement 108 by controlling the flow of fuel from the fuelsource 218 to one or more heating heads 218 through a fuel line 550. Inthe simplest control method, each fuel valve 548 is either on or off andmay be selectively changed between the two by an operator or a controlsystem (not shown). Any suitable control method for the fuel valve(s)548, either manual or automatic, may be used.

The heating zones 334 a, 334 b, and 334 c may each be associated with atleast one zone sensor (not shown). The zone sensor may be adapted tocontrol the fuel valve 548, and thereby the associated heating zone 334,to heat the pavement 108 to the predetermined temperature instead of orin addition to an operator who manually judges the heat of the pavement108 beneath each heating zone 334.

Although the exemplary embodiment uses heated air in combustion, theheating system 236 may also or instead supply heated air from theheating frame 230 directly to the pavement 108.

The furnace body 212 and associated structures can be made of relativelylighter materials when the heating system 236 is present than whichwould otherwise be needed to resist warping and other heat damage to theheating frame 230 or other structures of a primary or secondary furnacedevice 104 or 106 with no circulation of air. Therefore, use of theheating system 236 may result in cost savings in construction andoperation of the primary and secondary furnace devices 104 and 106. Theheating system 236 may even allow for use of the lighter multi-stageapparatus 100 on roads with a relatively thin roadbed substrate 110while avoiding load-related damage to the paved area 102 that heavierresurfacing equipment might cause.

FIG. 6 depicts a secondary furnace device 106 which may be used with themulti-stage apparatus 100. The secondary furnace device 106 is similarto the primary furnace device 104 and corresponding structures in bothwill be indicated by the same element numbers.

The secondary furnace device 106 is adapted to heat the paved area 102to a second predetermined temperature via a multi-stage process havingat least two heating zones 334 interspersed with at least one soakingzone 652. As shown in FIG. 6, each heating frame 230 of the secondaryfurnace device 106 is considered to be one heating zone 334 forsimplicity of description, though one of ordinary skill in the art couldreadily provide a plurality of heating zones 334 on each heating frame230 in a similar manner to the arrangement shown in FIGS. 3 a and 3 b,which may include providing at least first and second heating frames 230a and 230 b. Similarly, the soaking zone 652 which spaces apart theheating zones 334 in the secondary furnace device 106 of FIG. 6 isprovided by the positioning of the heating frames 230 in a spaced-apartconfiguration on the suspension frame 228 of the secondary furnacedevice. However, one of ordinary skill in the art could readily provideat least one soaking zone 652 interspersed between two or more heatingzones 334 on a single heating frame 230.

The secondary furnace device 106 includes two spaced-apart heatingframes 230 a, 230 b, in contrast to the primary furnace device 106, inwhich multiple heating frames 230 a, 230 b, when provided, are locateddirectly adjacent each other. In the embodiment shown in FIG. 6, eachheating frame 230 a, 230 b is associated with a separate fan 238. 238′and transmission duct 242, 242′ of the heating systems 236, 236′. Eachfan 238, 238′ circulates combustion air through the secondary furnacedevice 106 to cool the corresponding heating frame 230 a, 230 b,although it is contemplated that any number of fans 238, 238′ could eachbe associated with any number of heating frames 230 a, 230 b for aselected furnace device 104 or 106.

The rear heating frame 230 b (toward the right side of the view of FIG.6) of the secondary furnace device 106 is fixed to the suspension frame228, but may be selectively pivoted toward and away from the paved area102, as shown by arrow 654 and the phantom-line alternate positiondepiction of the heating frame in a raised position. The heightadjustment mechanism 232 of a pivotable heating frame may also beadapted for linear/sliding vertical movement of the heating frame, andmay be manually and/or automatically powered and controlled to adjust aheight of the heating frame over the paved area 102 as desired to bringthe pavement 108 to the appropriate predetermined temperature. Anyheating frame 230 of the multi-stage apparatus 100 could be configuredfor pivotal movement in the manner shown in FIG. 6 for the rear heatingframe 230 b of the secondary furnace device 106.

Multiple primary and/or secondary furnace devices 104 and 106 and otherstructures which heat the pavement 108 may be used in a singlemulti-stage apparatus 100 as desired in a particular paving orresurfacing operation. For example, and as shown in FIG. 1, a desiredmulti-stage apparatus 100 can include one primary furnace device 104,one secondary furnace device 106, and a heater/shaver 156, which will bediscussed below. The primary and secondary furnace devices 104 and 106,and any other heat-producing devices, may be adapted to providefunctions in addition to heating the pavement 108 to the predetermineddepth and temperature.

As shown in FIG. 7, the heater/shaver 156 includes a heating system 236and a plurality of heating heads 218, the heating heads being similar inoperation to those of the primary and secondary furnace devices 104 and106. An aggregate source 758 may be carried by the heater/shaver 156 oranother component of the multi-stage apparatus 100. When present, theaggregate source 758 may be adapted to selectively release aggregate(not shown), which may be loose rock or gravel, to the paved area 102 ata desired time during the operation of the multi-stage apparatus 100.For example, and as shown in FIGS. 1 and 7, the aggregate source 758 maybe positioned on the front of the heater/shaver 156 to release aggregateto the pavement 108 before the rest of the heater/shaver structuretravels over the pavement 108. The heater/shaver 156 is adapted to heatthe paved area 102 (and associated aggregate, when provided) to a thirdpredetermined temperature and depth. The heater/shaver 156 includes atleast one shaving blade 760 adapted to shave the paved area 102 to apredetermined depth and thereby create a first mixture 762 of loosepavement 108 and optional aggregate deposits located upon the substrate110. By “shave”, what is meant is that a portion of the pavement 108 ispried or cut away from the substrate 110 in a plowing or wedging mannerby a substantially longitudinal motion of the blade 760. The shavingblade(s) 760 may have a relatively sharp edge to sever the pavement 108from the substrate 110 or may be relatively blunt and remove thepavement 108 from the substrate 110 in much the same manner as asnowplow removing snow from a road surface. It is contemplated that theshaving blade 760 may be supported by a manually or automaticallypowered and/or controlled variable-height suspension system 764. Forexample, the variable-height suspension system 764 could operate via aspring action, and retract the shaving blade 760 from the paved area 102responsive to a predetermined resistance force to the shaving action. Inthis way, the shaving might only extend down through a heat-softeneddepth of the pavement 108 and thus avoid shaving of portions of thepavement 108 and/or substrate 110 if either has been inadequatelysoftened. Regardless of the mechanism of action, however, the shavingblade 760 is adapted to shave the pavement 108 from the paved area 102to a selectively variable shaving depth with assistance from thevariable-height suspension system, when present.

The shaving of the paved area 102 by the shaving blade(s) 760 may beaccomplished in multiple stages, either by multiple passes of theheater/shaver 156 or by multiple shaving blades 760 on the sameheater/shaver 156. The multiple shaving blades 760, when present, may betransversely offset across the longitudinal direction of the paved area102 to provide a total shaving width greater than the width of anindividual shaving blade 760. The structure, configuration, or positionof each shaving blade 760 may differ within a single configuration ofthe multi-stage apparatus 100. For example, at least one relativelylow-resolution dislodging-type shaving blade could make a rough pass toremove the bulk of the pavement 108, followed by at least onehigher-resolution smoothing-type shaving blade to smooth and even outthe shaved portions of the paved area 102. Alternately or additionally,a plurality of shaving blades could each be set at a different height togradually shave down to the predetermined depth. One of ordinary skillin the art could readily provide one or more shaving blades, dislodgingblades, and/or smoothing blades and associated components designed toprovide shaving functions having these or any other desired effects,finishes, and characteristics.

In some applications, the shaving of the pavement 108 may beaccomplished by a device which does not include a heat source such asthe depicted heating frame 230 and associated heating system 236 of theheater/shaver 156 of FIG. 1. Regardless of whether the heater/shaver 156includes a heating function, however, use of the shaving blade 760 toremove the pavement 108 results in a relatively smooth substrate 110 towhich new pavement 108 may readily adhere.

The heater/shaver 156 may be adapted to place the first mixture 762 onthe paved area 102 in a predetermined arrangement, for ease of latercollection and/or use, and this placement may be accomplished throughthe use of at least one material handling tool. For example, the shavingblades 760 or another material handling tool may be adapted to create atleast one windrow 766 of the first mixture 762, which may besubstantially arranged in a longitudinal direction along the substrate110 of the paved area 102. Optionally, one or more of the shaving blades760 may be selectively used to arrange the first mixture 762 intowindrows 766 without concurrently performing a shaving function. Anotherexample of a suitable material handling tool for arranging the firstmixture 762 as desired is a blunt shovel or plow (not shown) which canurge the first mixture 762 into the desired arrangement but is notsuited to performing a shaving operation.

During use of the multi-stage apparatus 100, at least one additivesource 768 may supply at least one additive to the first mixture 762after shaving and/or to the pavement 108 before shaving, or to anyincarnation of the pavement 108 and/or paved area 102 at any suitablestage of the pavement recycling process. Additional additive sources(not shown) may be provided to the heater/shaver 156 or anothercomponent of the multi-stage apparatus 100. For example, at least oneother additive source could be carried by the heater/shaver 156 at alocation spaced apart from the additive source 768. The additive(s) maybe applied directly to the pavement 108, to the windrow(s) 766 on thesubstrate 110, or to the first mixture 762 within a separate transportor mixing device. The additive may be, for example, a rejuvenating agentwhich acts in a known manner to refresh and renew the materialproperties of the asphalt (not shown) contained within the pavement. Theadditive, when present, may be applied in combination with a heatingoperation, depending upon the desired paving application. In someapplications of the present invention, and as described above, theadditive may be an aggregate, supplied to the first mixture 762 by theaggregate source 758. As used herein, the term “additive” refers to aliquid, solid, powder, gel, or any other suitable composition orsubstance, including aggregate rock, which is added to the paved area102, pavement 108, and/or substrate 110 from any source and at any timebefore, during, or after operation of the multi-stage apparatus 100, inorder to provide desired properties to recycled pavement produced by themulti-stage apparatus. The same additive, or type of additive, may beprovided multiple times during a single processing cycle, as well.

For example, a first additive may be provided to soften the pavement 108(optionally before the pavement is shaved), a second additive may beprovided to strengthen the pavement (optionally after the pavement hasbeen shaved), a third additive may be provided to strengthen the bondbetween individual components which make up the pavement (optionallyafter the pavement has been shaved), and a fourth additive—which may beaggregate—may be provided at any suitable time in the process to achievedesired physical properties in the final recycled pavement material.Regardless of the timing and/or nature of the additive(s) being added tothe first mixture 762, an auger 770 carried by the heater/shaver 156 maymix at least one additive and the first mixture 762 to form an additivemixture 772. The additive mixture 772, which may include additives fromthe aggregate source 758, additive source 768, and/or any other suitablesource, may be formed into the windrows 766 upon the substrate 110 asthe auger 770 ejects the additive mixture.

The windrows 766 may be formed by natural action of the auger 770 or maybe formed by one or more shaving blades 760 or by baffles (not shown)that direct the first mixture 762 or the additive mixture 772 to pileinto windrows 766. It is contemplated that the pavement 108 may begradually shaved to the desired depth by a series of passes ofsuccessive shaving blades 760 carried by one or more heater/shavers 156,and that the additive, when present, could be added at any suitable timeduring such a staged shaving operation. For simplicity, the followingdescription will refer to the “first mixture” as being the output of theheater/shaver 156. However, one of ordinary skill in the art willrecognize that, where a “first mixture” is referenced, an additivemixture 772 may be substituted in the referenced operation forapplications of the present invention in which one or more additives areused.

A pavement mixer/finisher 174, as depicted in the exemplary embodimentof FIGS. 1 and 8, is supported for movement along the paved area 102 bya suspension system 876. The mixer/finisher 174 includes a scoop 878 orother intake device adapted to collect the first mixture 762, eitherfrom windrows 766 formed by the shaving blades 760 or auger 770 or froma more random scattering across the substrate 110 of the paved area 102.The mixer/finisher 174 then mixes the first mixture 762 in a mixingplant 880 to produce recycled pavement 882, as shown in FIG. 8.

The mixing plant 880 includes a drum 884 extending substantiallyparallel to the paved area 102 and an auger 886 located within the drum884. As can be seen in FIG. 8, the drum 884 may be slightly tiltedupward from the paved area 102, but a slight slope angle (such as thatshown) of 15° or less is considered to be “substantially parallel”, asused herein. The auger 886 is rotatable relative to the drum 884. Theauger 886 may include paddles, posts, or other protrusions (such as thepaddle shown schematically at 888) to assist in breaking up and mixingthe first mixture 762 into recycled pavement 882 as the first mixture762 travels through the drum 884. As shown in FIG. 8, the auger 886 mayinclude a rotatable helical flange 890. When present, the helical flange890 may have a pitch in the range of 20-30° from the vertical. Anydesired number and configuration(s) of paddle(s) 888 or otherprotrusions may extend from any surface of the mixing plant 880 and mayhave any desired orientations; for example, the paddles may be locatedat 25° intervals around the circumference of the helical flange 890.

The mixer/finisher 174 may heat the first mixture 762 before, during,and/or after mixing, through the use of ambient or externally-providedheat, heat provided by other components of the multi-stage apparatus,and/or heat generated by or within the mixer/finisher itself, whichcould be accomplished with a heating system 236 much like those of theprimary and secondary furnace devices 104 and 106. Also, themixer/finisher 174 may include at least one additive source 768 which isadapted to supply at least one additive, such as a rejuvenating agent oran aggregate, to the first mixture 762 within the mixing plant 880,before, during, and/or after mixing and either in addition to, orinstead of, an earlier-added additive. For example, one or more additivesources 768, adapted to supply any or all of the aforementioned first,second, and third additives to the first mixture 762, may be associatedwith the mixing plant 880. Regardless of the additive(s) supplied ormechanical operations which occur, the mixing plant is adapted totransform the first mixture 762 into recycled pavement 882.

Just as the scoop 878 or another intake device (not shown) may beadapted to deliver the first mixture 762 to the mixing plant 880, abaffle 892 or other output device (not shown) may be adapted to helpdeliver the recycled pavement 882 from the mixing plant. The baffle 892(seen from the side in the view of FIG. 8) may help in controllablyrouting the recycled pavement 882 into a scattering or freefall onto thepaved area 102 behind the mixer/finisher 174. When present, the baffle892 may be a simple shaped plate, or may include additional manually orautomatically actuated and/or powered moving components.

Additionally or alternatively to the baffle 892, one or more plow blades894 may be provided on the mixer/finisher 174 to assist with placementof the recycled pavement 882 into a desired arrangement on the pavedarea 102, such as into windrows (not shown) similar to those produced bythe heater/shaver 156. Once the recycled pavement 882 is on the pavedarea 102, the recycled pavement may be collected for later use orre-installed onto the original paved area. It is also contemplated thatthe recycled pavement 882 may be ejected directly from the mixing plant880 into a hopper (not shown) carried by the mixer/finisher 174, or intoa trailer (not shown) or other separate transportation device for use inanother location and/or at a later time.

Multiple primary and/or secondary furnace devices 104 and 106, no matterwhat additional functions may be provided by each, may travel in serieswith at least one heater/shaver 156 and mixer/finisher 174 in alongitudinal direction along the paved area 102 to comprise themulti-stage apparatus 100 depicted in FIG. 1 (the longitudinal directionbeing from right to left along the plane of the page of FIG. 1). Suchsequential travel may include a physical connection between successiveprimary and secondary furnace devices 104 and 106, the heater/shaver156, and the mixer/finisher 174, as shown by the connections A-A, B-B,and C-C of FIG. 1. Any of the primary and secondary furnace devices 104and 106, the heater/shaver 156, and the mixer/finisher 174 may becontrolled to the extent desired by a central controller (not shown) ofthe multi-stage apparatus 100. Alternatively, primary and secondaryfurnace devices 104 and 106, the heater/shaver 156, and themixer/finisher 174 may be used separately and/or in any combination ororder with each other as desired for a particular paving operation.

In use, an operator evaluates a paved area 102 to determine theproperties of the existing pavement 108 and responsively produces aformal or informal plan for removing and/or recycling the material ofthe paved area. This plan might include the provision of calculatedvalues for the first, second, third, and fourth predeterminedtemperatures, as well as the specification of specific types and amountsof additives for use in the process. Additionally, a direction and/orspeed of travel of the multi-stage apparatus 100 across the paved area102 may be specified. It is contemplated, however, that the plan may bereadily changed as desired during operation of the multi-stage apparatus100.

Once the preliminary planning steps have been completed, the multi-stageapparatus 100 travels in a longitudinal direction along the paved area102 which is to be resurfaced. The primary furnace device 104 passesover the paved area 102, supplies heat to the pavement 108 from theheating heads 218, and controls the temperature of the pavement 108associated with each heating zone 334. The operator of the primaryfurnace device 104 manually or automatically controls the height andactuation of the heating heads 218 in each heating zone 334, separatelyor together, to bring the pavement 108 to the first predeterminedtemperature.

Once the primary furnace device 104 has passed over a section of thepavement 108, that section rests or soaks for a period of time to allowthe applied heat to penetrate from the very top surface of the pavement108 into the depth of the pavement 108 toward the substrate 110. Thissoaking period may prevent scorching or burning of the top of thepavement 108 while still achieving a suitable temperature rise throughthe depth of the pavement 108 to provide desired resurfacing properties.

Next, a secondary furnace device 106 passes over the same section of thepaved area 102 that was previously heated by the primary furnace device104. The secondary furnace device 106 applies heat to the pavement 108in a similar manner to that of the primary furnace device 104, to bringthe pavement 108 to a second predetermined temperature. However, and aspreviously discussed, the secondary furnace device 106 includes firstand second (and optionally additional) heating zones 334 fixedlyconnected to each other and spaced apart from each other. Accordingly,the secondary furnace device 106 heats the paved area 102 to a secondpredetermined temperature via a multi-stage process with at least twoheating periods (each heating period associated with the passage of aheating zone 334 over the paved area) interspersed with at least onesoaking period (each soaking period associated with the lack of aheating zone 334 over the paved area). The pavement 108 may then be onceagain permitted to soak in the applied heat.

Once the primary and secondary furnace devices 104 and 106 have passedover the paved area 102 in the exemplary embodiment of the multi-stageapparatus 100 shown in FIG. 1, the heater/shaver 156 may pass over thepaved area. The heating frame 230 of the heater/shaver 156 may heat thepaved area 102 to a third predetermined temperature, either in a singlestep or via a multi-stage process like that of the secondary furnacedevice 106. Optionally, a soaking zone 652 may be provided once theheating frame 230 of the heater/shaver 156 has passed the paved area102.

As shown in FIG. 1, once the paved area 102 reaches the thirdpredetermined temperature, at least one shaving blade 760 shaves awaythe pavement 108 from the substrate 110 of the paved area 102 to adesired depth. The depth of shaving may be predetermined or may bedetermined during the shaving process responsive to a factor such as apenetration depth of heat applied by other component(s) of themulti-stage apparatus 100. The shaving blade(s) 760 optionally pile theresulting first mixture 762 (comprised mainly of loose pavement 110,along with some amount of dirt and debris; an additive such as aggregatemay be provided to the first mixture) into at least one windrow 766 uponthe substrate 110. One or more additives may be added to the windrow(s)766 of the first mixture 762 by an additive source 768, such as a liquidsprayer or pellet hopper, located at an appropriate position on theheater/shaver 156. The additive, when present, could instead or also beadded to the pavement 108 before or after shaving or before or after thepaved area 102 is heated.

In the exemplary embodiment of FIG. 1, an auger 770 may optionallygather the windrows 766 of the first mixture 762 lying atop thesubstrate 110 of the paved area 102, optionally after aggregate or oneor more other additives have been added to the windrows 766. When anadditive is provided directly to the first mixture 762 (which may occurbefore or after the first mixture has been placed in windrows 766), theauger 770 mixes the additive and the first mixture 762 to produce anadditive mixture 772, which is then ejected from the auger 770 onto thesubstrate 110. The auger 770 may be configured, positioned, and/orcontrolled to shape the resulting windrows or loose piles of additivemixture 772 as desired. It is to be understood that the term “firstmixture” 762, as used herein, may comprise any desired additive mixture.

In another optional operation of the multi-stage apparatus 100 of FIG.1, an aggregate (not shown) may be supplied to the first mixture 762,for example, by an aggregate source 758 or another additive source 768of the heater/shaver 156, at any time before, during, or after shavingof the pavement 108 to form the first mixture 762. The aggregate, whenpresent, could be mixed into the first mixture 762 to form an aggregatemixture (not shown) in a similar manner to the formation of the additivemixture previously discussed. Such an aggregate mixture will also beunderstood to comprise an additive mixture 772, for purposes of theinstant discussion.

The aggregate could passively absorb heat from the first mixture 762during a soaking period after the aggregate has been added to the firstmixture. Alternately, the combination of the aggregate and the firstmixture 762 may be actively heated to a fourth predeterminedtemperature, again optionally using a zone system including a heatingframe (not shown) incorporating heating heads (not shown) to achieve thefourth predetermined temperature. The aggregate and first mixture 762could then be allowed to soak at the fourth predetermined temperature.

A mixer/finisher 174 travels behind the heater/shaver 156 of the FIG. 1exemplary embodiment and collects the windrows 766 of the first mixture762 (or of any optional aggregate mixture or additive mixture, asappropriate), optionally with a scoop 878. The mixer/finisher 174 mayheat the first mixture 762; add any desired additive, such as aggregateand/or one or more of the first, second, and third additives; mix thefirst mixture more thoroughly; add heat to, and/or remove heat from, thefirst mixture 762; and/or otherwise manipulate the first mixture toproduce recycled pavement 882 having desired properties. The scoop 878supplies the first mixture 762 to the mixing plant 880, which uses therotational motion between the auger 886 and the drum 884 to mix thefirst mixture into recycled pavement 882. For example, whether or not anadditive of any type was previously provided to the first mixture 762,the mixer/finisher 174 may mix the first mixture within the drum 884 fora time period of at least ninety seconds. The newly-formed recycledpavement 882 may be left on the substrate 110 of the paved area 102 ormay be transferred from the mixing plant 880 to a paver hopper (notshown) or another paving material collection/transport device, such as adump truck (not shown). The recycled pavement 882 may then be used withany suitable paving method for resurfacing of the paved area 102 or maybe transported to another area to surface or resurface a different pavedarea.

In the embodiment shown in FIG. 1, the steps of heating the paved area102 to the first predetermined temperature, heating the paved area 102to the second predetermined temperature, heating the paved area 102 tothe third predetermined temperature, shaving the heated paved area 102,collecting the first mixture 762, mixing the first mixture 762, andproducing recycled pavement 882 occur in series. Optionally, thesesteps, in addition to occurring serially, also occur in the listedsequence.

While aspects of the present invention have been particularly shown anddescribed with reference to the preferred embodiment above, it will beunderstood by those of ordinary skill in the art that various additionalembodiments may be contemplated without departing from the spirit andscope of the present invention. For example, the heating system 236 maysupply heated air to the heating heads 218 or pavement 108 in adifferent manner than described; one or more heating frames 230 of eachfurnace device 104 and 106 may be vertically movable with respect to thepaved area 102 in a linear and/or pivoting manner; the transmission duct242 and other components of the heating system 236 may be flexible,segmented, or otherwise adapted to facilitate height adjustment of anassociated heating frame 230; the multi-stage apparatus 100 couldinclude at least one secondary furnace device 106 and no primary furnacedevice 104; two or more of the first, second, third, and fourthpredetermined temperatures may be substantially the same temperature; auser of the secondary furnace device 106 could provide at least onesoaking zone 652 or soaking period by simply declining to activate atleast one heating zone 334 to simulate a spacing-apart of the adjacentheating zones; each primary and secondary furnace device 104 and 106,heater/shaver 156, and mixer/finisher 174 may be pushed, towed, orself-propelled; the primary and secondary furnace device 104 and 106,heater/shaver 156, and mixer/finisher 174 may each be controlledremotely or on-board; several of the heating, additive-adding, shaving,and mixing functions may be combined in a single furnace device 104 or106; or various mixtures of pavement 108 and an additive such asrejuvenating agent and/or aggregate may be combined and mixed atdifferent times than those described above. However, a device or methodincorporating such an embodiment should be understood to fall under thescope of the present invention as determined based upon the claims belowand any equivalents thereof.

Other aspects, objects, and advantages of the present invention can beobtained from a study of the drawings, the disclosure, and the appendedclaims.

1. An apparatus comprising: a primary furnace device adapted to heat apaved area to a first predetermined temperature; a secondary furnacedevice adapted to heat the paved area to a second predeterminedtemperature via a multi-stage process having at least two heating zonesinterspersed with at least one soaking zone; a heater/shaver adapted toheat the paved area to a third predetermined temperature and to shavethe heated paved area to a predetermined depth to create a first mixturelocated upon a substrate; and a mixer/finisher adapted to collect thefirst mixture, mix the first mixture, and produce recycled pavement; theprimary furnace device, secondary furnace device, heater/shaver, andmixer/finisher traveling in series along the paved area in alongitudinal direction.
 2. The apparatus of claim 1, wherein theheater/shaver includes a shaving blade supported by a variable-heightsuspension system, the shaving blade being adapted to shave the pavementfrom the paved area to a variable shaving depth responsive to thevariable-height suspension system.
 3. The apparatus of claim 1, furthercomprising at least one aggregate source adapted to supply aggregate tothe first mixture.
 4. The apparatus of claim 1, further comprising atleast three additive sources adapted to supply at least three additivesto the first mixture.
 5. The apparatus of claim 1, wherein themixer/finisher includes: a suspension system adapted to support themixer/finisher for movement along a paved area; a mixing plant includinga drum and an auger, the auger being rotatable relative to the drum, thedrum extending substantially parallel to the paved area, and the mixingplant being adapted to transform the first mixture into recycledpavement; an intake device adapted to deliver the first mixture to themixing plant; and an output device adapted to deliver the recycledpavement from the mixing plant.
 6. The apparatus of claim 5, wherein theauger includes a rotatable helical flange, and the pitch of the flangeis in the range of 20-30 degrees from the vertical.
 7. The apparatus ofclaim 5, wherein the mixing plant includes at least two additivesources, adapted to supply at least two additives to the first mixturewithin the mixing plant.
 8. The apparatus of claim 5, wherein the mixingplant is configured to mix the first mixture for a time period of atleast ninety seconds.
 9. The apparatus of claim 5, wherein the mixingplant is configured to add heat to the first mixture during the mixingprocess.
 10. The apparatus of claim 1, wherein the primary furnacedevice heats the paved area to the first predetermined temperature usinga plurality of adjacent heating zones.
 11. The apparatus of claim 10,wherein at least one heating zone includes an air box adapted to directairflow to at least one heating head through at least one circulationduct.
 12. The apparatus of claim 1, wherein the heater/shaver is adaptedto place the first mixture on the paved area in a predeterminedarrangement.
 13. The apparatus of claim 12, wherein the heater/shaverincludes at least one material handling tool adapted to place the firstmixture in the predetermined arrangement.
 14. A furnace device forheating pavement during a paving operation, the furnace devicecomprising: a heating system with a plurality of heating zones, theplurality of heating zones being arranged in a longitudinal directionrelative to the direction of movement of the furnace device relative tothe pavement, each of the heating zones being separately controllableand spaced apart from each other by at least one soaking zone; and asuspension system that supports the plurality of heating zones formovement along the paved area.
 15. The furnace device of claim 14,further comprising: a heating frame and a heating system for heating thepavement, the heating frame being adapted to support at least oneheating zone, and the heating system being adapted to circulatecombustion air through the furnace device to cool the heating frame. 16.The furnace device of claim 15, wherein an air box directs combustionair to at least one heating head through at least one circulation duct.17. A pavement mixer/finisher for processing pavement during a pavingoperation, the mixer/finisher comprising: a suspension system adapted tosupport the mixer/finisher for movement along a paved area; a mixingplant including a drum and an auger, the auger being rotatable relativeto the drum, the drum extending substantially parallel to the pavedarea, and the mixing plant being adapted to transform the first mixtureinto recycled pavement; an intake device adapted to deliver the firstmixture to the mixing plant; and an output device adapted to deliver therecycled pavement from the mixing plant.
 18. The pavement mixer/finisherof claim 17, wherein the auger includes a rotatable helical flange, andthe pitch of the flange is in the range of 20-30 degrees from thevertical.
 19. The pavement mixer/finisher of claim 17, wherein themixing plant includes at least two additive sources, adapted to supplyat least two additives to the first mixture within the mixing plant. 20.The pavement mixer/finisher of claim 17, wherein the mixing plant isconfigured to mix the first mixture for a time period of at least ninetyseconds.
 21. The pavement mixer/finisher of claim 17, wherein the firstmixture is heated within the mixing plant.
 22. A method of recyclingpavement, the method comprising the steps of: heating a paved area to afirst predetermined temperature; heating the paved area to a secondpredetermined temperature via a multi-stage process with a furnacedevice having first and second heating zones fixedly connected to eachother and spaced apart from each other; heating the paved area to athird predetermined temperature; shaving the heated paved area to apredetermined depth to create a first mixture located upon a substrate;collecting the first mixture; mixing the first mixture; and producingrecycled pavement; wherein the steps of heating the paved area to thefirst predetermined temperature, heating the paved area to the secondpredetermined temperature, heating the paved area to the thirdpredetermined temperature, shaving the heated paved area, collecting thefirst mixture, mixing the first mixture, and producing recycled pavementoccur in series.
 23. The method of claim 22, wherein the steps ofheating the paved area to the first predetermined temperature, heatingthe paved area to the second predetermined temperature, heating thepaved area to the third predetermined temperature, shaving the heatedpaved area, collecting the first mixture, mixing the first mixture, andproducing recycled pavement occur in the listed sequence.
 24. The methodof claim 22, wherein at least one of the steps of mixing the firstmixture and producing recycled pavement include the steps of supplyingaggregate to the first mixture; and supplying at least three additivesto the first mixture.
 25. The method of claim 22, including the step ofproviding a mixing plant including a drum and an auger, the auger beingrotatable relative to the drum, the drum extending substantiallyparallel to the paved area, and wherein the steps of mixing the firstmixture and producing recycled pavement are both performed by the mixingplant.
 26. The method of claim 22, wherein the step of mixing the firstmixture occurs for a duration of at least ninety seconds.
 27. The methodof claim 22, wherein the step of mixing the first mixture includes thestep of providing heat to the first mixture.
 28. The method of claim 22,including the steps of: evaluating a paved area to determine theproperties of the existing pavement; and responsively producing a planfor recycling the material of the paved area.
 29. A system for recyclingpavement, the system comprising: means for heating a paved area to afirst predetermined temperature; means for heating the paved area to asecond predetermined temperature via a multi-stage process with at leasttwo heating periods interspersed with at least one soaking period, themeans for heating the paved area to a second predetermined temperatureincluding a furnace device having first and second heating zones fixedlyconnected to each other and spaced apart from each other; means forheating the paved area to a third predetermined temperature; means forshaving the heated paved area to a predetermined depth to create a firstmixture located upon a substrate; means for collecting the firstmixture; means for mixing the first mixture; and means for producingrecycled pavement; wherein the means for heating the paved area to thefirst predetermined temperature, means for heating the paved area to thesecond predetermined temperature, means for heating the paved area tothe third predetermined temperature, means for shaving the heated pavedarea, means for collecting the first mixture, means for mixing the firstmixture, and means for producing recycled pavement operate in seriesalong the paved area in a longitudinal direction.
 30. The system ofclaim 29, wherein the means for heating the paved area to the firstpredetermined temperature, means for heating the paved area to thesecond predetermined temperature, means for heating the paved area tothe third predetermined temperature, means for shaving the heated pavedarea, means for collecting the first mixture, means for mixing the firstmixture, and means for producing recycled pavement operate in the listedsequence.
 31. The system of claim 29, including means for adding atleast three additives to the first mixture.
 32. The system of claim 29,including means for heating the first mixture during mixing.